• Structural Engineering and Mechanics
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• 제87권6호
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• pp.555-574
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• 2023

An efficient optimization algorithm and damage-sensitive objective function are two main components in optimization-based Finite Element Model Updating (FEMU). A suitable combination of these components can considerably affect damage detection accuracy. In this study, a new hybrid damage-sensitive objective function is proposed based on combining two different objection functions to detect the location and extent of damage in structures. The first one is based on Generalized Pseudo Modal Strain Energy (GPMSE), and the second is based on the element's Generalized Flexibility Matrix (GFM). Four well-known population-based metaheuristic algorithms are used to solve the problem and report the optimal solution as damage detection results. These algorithms consist of Cuckoo Search (CS), Teaching-Learning-Based Optimization (TLBO), Moth Flame Optimization (MFO), and Jaya. Three numerical examples and one experimental study are studied to illustrate the capability of the proposed method. The performance of the considered metaheuristics is also compared with each other to choose the most suitable optimizer in structural damage detection. The numerical examinations on truss and frame structures with considering the effects of measurement noise and availability of only the first few vibrating modes reveal the good performance of the proposed technique in identifying damage locations and their severities. Experimental examinations on a six-story shear building structure tested on a shake table also indicate that this method can be considered as a suitable technique for damage assessment of shear building structures.

• Ocean Science Journal
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• 제43권4호
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• pp.165-173
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• 2008

In this article, we describe a simple yet effective method for insertion of observational datasets in a mesoscale atmospheric model used in one-dimensional configuration through Nudging. To demonstrate the effectiveness of this technique, vertical profiles of meteorological parameters obtained from GLASS Sonde launches from a tiny island of Kaashidhoo in the Republic of Maldives are injected in a mesoscale atmospheric model - Advanced Regional Prediction System (ARPS), and model simulated parameters are compared with the available observational datasets. Analysis of one-time nudging in the model simulations over Kaashidhoo show that incorporation of this technique reasonably improves the model simulations within a time domain of +6 to +12 Hrs, while its impact on +18 Hrs simulations and beyond becomes literally null.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1991년도 추계학술발표회 논문집 지반공학에서의 컴퓨터 활용 COMPUTER UTILIZATION IN GEOTECHNICAL ENGINEERING
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• pp.312-331
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• 1991

런던시내의 역사적 건물들 주변에서 LONDON CLAY층을 굴착하고 지하 5층의 주차장 건설에 TOP-DOWN공법이 적용되었다. 인접 구조물들의 안전진단을 수치해석(F.E.M)으로 예측하고 현장에서 실측한 자료와 비교분석하였다. 사용된 탄소성 COMPUTER 모델은 현장계측값들과 비교적 잘 일치하고 있으며, 지하 연속벽(DIAPHRAGM WALL)을 이용한 TOP-DOWN공법이 주변지반 변형을 감소시킬 수 있는 가장 효과적인 방법으로 판명되었다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.357-364
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• 2000

The three main processes involved in the design of stressed membrane surface are surface form-finding, stress analysis and cutting pattern generation. The last process, cutting pattern generation, is considered as a very important procedure in the aspect of the practical design for the fabric membrane surface. In this paper, The cutting pattern generation technique using the geodesic line algorithms is first introduced. And the numerical examples resulting from this technique are presented. Cable elements are used for the approximating membrane surface and two kinds of model, square line and central line model, are used in pattern generation. Finally, a number of different cutting pattern generation for the same membrane surface is carried out and the numerical results are compared each

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.324-331
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• 2000

In this study, a new algorithm analyzing dynamic crack propagation problem by the coupling technique of Meshfree Method and Finite Element Method is proposed. The coupling procedure of two methods is presented with a short description of Meshfree Method especially, Element-free Galerkin (EFG) method. The elastodynamic fracture theory is presented, and a numerical implementation procedure for dynamic fracture analysis by Meshfree Method is also discussed. A couple of dynamic crack propagation problems illustrate the performance of the propsed technique. The accuracy of numerical solutions by the developed algorithm are compared with those of analytical solutions and experimental ones.

• 전자공학회논문지B
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• 제29B권11호
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• pp.36-45
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• 1992

A numerical trajectory planning method for path-constrained trajectory planning is proposed which ensures collision-free and time-optimal motions for two robotic manipulators with limited actuator torques and velocities. For each robot, physical constraints of the robots such as limited torques or limited rotational velocities of the actuators are converted to the constraints on velocity and acceleration along the path, which is described by a scalar variable denoting the traveled distance from starting point. Collision region is determined on the coordination space according to the kinematic structures and the geometry of the paths of the robots. An Extended Coordination Space is then constructed` an element of the space determines the postures and the velocities of the robots, and all the constraints described before are transformed to some constraints on the behaviour of the coordination-velocity curves in the space. A dynamic programming technique is them provided with on the discretized Extended Coordination Space to derive a collision-free and time-optimal trajectory pair. Numerical example is included.

• 대한기계학회논문집
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• 제19권6호
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• pp.1363-1370
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• 1995

A nonlinear dynamic modeling method for simply supported structures undergoing large overall motion is suggested. The modeling method employs Rayleigh-Ritz mode technique and Von Karman nonlinear strain measures. Numerical study shows that the suggested modeling method provides qualitatively different results from those of the Classical Linear Cartesian modeling method. Especially, natural frequency variations and residual deformation due to membrane strain effects are observed in the numerical results obtained by the suggested modeling method.

• 터널과지하공간
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• 제2권1호
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• pp.164-176
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• 1992

The conical-ended borehole technique and hemispherical-ended borehole technique are proposed, for the accurate stress measurement within a rock mass. Theory of stress tensor determination and in situ measurement system are presented with successful case examples, and the characteristics of stress distribution within rock masses are examined by the multiple times measurement in a single borehole. Subsequently, the problem in relation to the numerical approach for cavern designing is discussed on the basis of the dependency of the stress discontinuity on the geological discontinuities and so on.

• 한국전산유체공학회지
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• 제13권3호
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• pp.8-13
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• 2008

We present a numerical simulation technique and some preliminary results of the impact and spreading of a droplet containing particles on the solid substrate in 2D. We used the 2nd-order Adams-Bashforth / Crank-Nicholson method to solve the Navier-Stokes equation and employed the level-set method with the continuous surface stress for description of droplet spreading with interfacial tension. The impact velocity has been generated by the instantaneous gravity. The distributed Lagrangian-multipliers method has been combined for the implicit treatment of rigid particles and the discontinuous Galerkin method has been used for the stabilization of the interface advection equation. We investigated the droplet spreading by the inertial force and discussed effects of the presence of particles on the spreading behavior using an example problem. We observed reduced oscillation and spread for the particulate droplet.

• 환경영향평가
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• 제19권3호
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• pp.307-314
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• 2010

Brebbia's model has been analyzed to develop the appropriate waterworks management system in Korea, and compared with the conventional models such as EPANET, WaterCad, and InfoWorks. The hydraulic theory of the models was analyzed. Each model's numerical techniques, required parameters, input data and operational methodologies, restrictions, practical applicability and other aspects were investigated. In order to check the validity of Brebbia model, the comparative analysis with EPANET, WaterCAD, and InfoWorks models was performed for linear and nonlinear cases. To find out advantages and disadvantages of each model, the modeling was performed for a simple network and for more complicated A city waterworks system, and the three models applicability was examined. Finally, optimal modeling technique and a model suitable for the use in Korea was suggested, and the problems related to present projects of waterworks management system in Korea were analyzed.